1. Field of the Invention
The present invention generally relates to a power supply cable and, more particularly, to a power supply cable for supplying electric power to a light source carried by a movable object used in an image reading apparatus such as, for example, a copying machine or a facsimile machine which is provided with a scanner having a light source attached to a movable carriage.
2. Description of the Related Art
Conventionally, a flexible power supply cable is used so as to supply electric power to a load such as a light source carried by a movable carriage, which together constitute a scanner provided in an image reading apparatus such as a copying machine or a facsimile machine.
One of the conventional flexible power supply cables is a flexible printed circuit board (hereinafter referred to as FPC). The FPC comprises a flexible insulating sheet and conductive wire patterns printed on the flexible insulating sheet. A protective sheet is applied on the conductive wire patterns so that the conductive wire patterns are interposed between the flexible insulating sheet and the protective sheet.
Such an FPC is not directly connectable with a power supply terminal of a light source or a power supply terminal of an apparatus. Accordingly, a printed board is attached to each end of the FPC so as to connect electric wires to the FPC. More specifically, an end of each conductive wire pattern of the FPC is soldered to the printed board, and the electric wire is also soldered to the printed board so that the conductive wire pattern is connected to one end of the corresponding electric wire. Then, the other end of the electric wire is connected to the power supply terminal of the light source or the apparatus.
Alternatively, an electric connector is attached to the printed board by soldering, and another electric connector is soldered to an end of the electric wire so that the electric connector of the electric wire is connectable to the electric connector of the printed board for electrical connection.
Further, Japanese Patent Publication No. 2588605 discloses anther conventional power supply cable in which each end of the FPC is connected to the electric wire by an exclusive relay connector.
The above-mentioned conventional power supply cables are used by being connected to a power supply terminal of a light source at its one end and to a power supply terminal of the apparatus at its opposite end. Since the FPC is flexible and bendable, a movement of the end of the FPC connected to the light source is permitted. Accordingly, electric power can be supplied from the power supply terminal of the apparatus to the power supply terminal of the light source via the FPC. In order to allow the light source to move a long distance, the FPC is connected in a bent state like a U-shape. A protective member is applied to the surface of the FPC on the outer side of the U-shape.
The above-mentioned structures using the FPC as a power supply cable has a problem in that a manufacturing cost is high since the cost of the FPC itself is expensive and the number of parts constituting the power supply cable is large. The manufacturing cost is further increased since the structure of the power supply cable is complex and the number of manufacturing processes is large. Further, a large labor may be needed for repair at the time of failure since the number of manufacturing processes is high.